A downhole coupling connects adjacent members of a string of tools, rods, or tubing together within a well. A shear coupling may be positioned near the base of a sucker rod string above a downhole pump. Now and then the pump may get stuck, for example, if a well has scale or paraffin problems. A shear coupling provides a mechanism for releasing the drive rod from the pump by pulling on the rod with a tension sufficient to shear a set of pins positioned in the coupling. After separation the rod is free to be pulled out of the well independent of the pump.